Chyluria

Chyluria Definition

Chyluria or chylous urine is a condition with the presence of chyle in the urine, which results in milky urine. Chyle is a body fluid within the lymphatic vessels, which conveys the digested fat from the small intestine to the blood. Chyle consists of the lymph and lipid particles called chylomicrons, which are composed of fats and proteins [1].

Symptoms and Signs

Chyluria can be a debilitating condition that can have an intermittent (waxing and waning) and recurrent course [2]. The main symptom is thick, milky and possibly foamy urine [2]. Other symptoms and signs can include frequent and burning urination (dysuria), passing fat or blood clots, pinky or red urine due to the blood (hematuria), kidney pain, weakness, weight loss, fever and swelling of the legs or scrotum (hydrocele) [2,3]. Chyluria by itself is not life-threatening [4].

Chyluria is rare in the United States and Europe. It occurs in South Asia, Africa and Central and South America, mainly in rural areas with the abundance of mosquitoes that spread the parasite Wuchereria bancrofti, which causes filariasis [2,3,4]. The condition is more common in men than in women [3].

Causes And Pathophysiology

Causes of chyluria include [2,3]:

An obstruction of the lymphatic vessels in the kidneys resulting in the backflow of the lymph into the urine due to parasitic infestations (filariasis, schistosomiasis, ascariasis, echinococcosis, cysticercosis, dwarf tapeworms and malaria), tuberculosis, congenital disorders of the lymphatic vessels, lymphangioma of the urinary tract, kidney trauma or surgery, pernicious anemia or diabetes mellitus

An obstruction of the thoracic duct (a major lymphatic vessel) due to an aortic aneurysm or cancer in the chest cavity, or pregnancy, which results in the backflow of chyle toward the kidneys

An abnormal connection (fistula) between the lymphatic vessels and a part of the urinary tract, such as the urinary bladder (rare; in children)

Nephrotic syndrome with an excessive excretion of proteins and fats into the urine (proteinuria and lipiduria)

Chart 1. Diagnostic Tests for Chyluria

TEST

EXPECTED TEST RESULT

Urine tests

The disappearance of milky urine after a fat-free diet

Clearance of urine after adding ether

Increased albumins in the morning urine

Increased triglycerides and chylomicrons after a fatty meal

Blood tests

The parasite Wuchereria bancrofti detected by the immunochromatographic test

X-ray ((lymphangiography, intravenous urography or retrograde pyelography): a site of the chyle leakage

Ultrasound: a chylous clot in the bladder

Chart 1 references: 2,3,4,5

Conditions Similar To Chyluria

Apart from chyluria, milky urine can also appear in other conditions:

Urinary tract infections

Sexually transmitted diseases

Kidney inflammation

Nephrotic syndrome

Treatment

Chyluria often resolves spontaneously or with conservative measures, such as a low-fat diet [2].

Diet

Reducing fats in the diet decreases the excretion of fat into the urine and thus milky urine [2,3]. The intake of long-chain fatty acids (most fats and oils, especially ghee) should be replaced by the intake of medium-chain fatty acids (coconut oil), which are absorbed directly into the blood and not into the lymph and are therefore not excreted into the urine [2,4]. High intake of proteins is intended to replace the proteins lost in the urine [2].